This relates generally to electronic devices and, more particularly, to displays for electronic devices.
Electronic devices such as cellular telephones, computers, and media players often contain displays. For example, electronic devices often include backlit displays such as backlit liquid crystal displays.
Backlit displays generally include a light distribution layer called a light guide plate. The light guide plate is typically formed from a rectangular sheet of clear plastic that has been injection molded, extruded, or die cut from a sheet of plastic. Light from an array of light-emitting diodes may be launched into the edge of the light guide plate. The light guide plate distributes light across the back of a display panel by total internal reflection. Light that exits the planar upper surface of the light guide plate serves as backlight for the display panel.
The light guide plate is typically mounted within a white plastic chassis structure that is sometimes referred to as a p-chassis or moldframe. The white plastic of the p-chassis forms reflective sidewalls around the periphery of the light guide plate. Light that exits the edges of the light guide plate is reflected back into the light guide plate by the reflective sidewalls of the p-chassis. The reflected light may therefore serve as additional backlight for the display.
The use of reflective white plastic to form the p-chassis can improve backlight efficiency. However, the white plastic that forms the sidewalls of the p-chassis is generally unable to block all of the light that strikes the sidewalls. As a result, some of the light from the light guide plate can leak into undesired areas of an electronic device. If care is not taken, for example, leaking light may cause unwanted illumination in locations that are visible to a user of an electronic device.
It would therefore be desirable to be able to provide improved display backlight structures such as improved chassis structures for light guide plates in display backlights.